This invention relates generally to an improved sports boot of the type adapted for use by snow skiers, ice skaters, and the like. More particularly, this invention relates to an improved sports boot of the type requiring close mechanical coupling of a person's foot and lower leg region with an outer boot shell.
In the sport of snow skiing, it is well known to provide a ski boot adapted for releasable yet substantially rigid mechanical attachment to a snow ski. Such rigid ski boots typically include a relatively tall outer boot shell of substantially rigid construction designed to extend upwardly about the skier's foot and ankle and further about a region of the skier's lower leg. Such ski boots are conventionally designed to fit the skier's foot in a relatively tight manner to obtain an optimum mechanical coupling between a snow ski and the person's foot. This close mechanical coupling is required to insure accurate and stable ski movements in response to foot and leg movements for enhanced ski performance. Similar mechanical considerations are also encountered in other types of sports footwear, for example, in ice skates and the like requiring close mechanical coupling between the foot and a mechanical implement, e.g. the skate blade.
In the past, ski boots and other similar types of athletic footwear have been designed with a high degree of mechanical stiffness in an effort to optimize mechanical coupling between the foot and the snow ski or other implement. However, such rigid boots inherently tend to be significantly uncomfortable whereby substantial cloth and/or foam padding are normally provided between the skier's foot and the rigid outer boot shell in an effort to provide some degree of user comfort. This cloth and/or other padding material unfortunately accommodates relative foot motion with respect to the outer boot shell and thereby at least partially defeats the desired close mechanical coupling. Moreover, the addition of cloth and/or other padding material does not by itself accommodate foot size changes which can occur during the course of a day, for example, due to temperature induced swelling or contraction of the foot, whereby the boot can still become uncomfortably tight or undesirably loose unless periodic boot size adjustments are made.
A wide variety of ski boot designs have been proposed over the years for achieving improved mechanical coupling between the skier's foot and a substantially rigid outer boot shell. Such designs include, by way of example, inflatable boot liners adapted to receive and contain a supply of air under pressure and/or to receive a curable foam elastomer substance, wherein the bladders are designed to conform with the specific shape of a person's foot when the boot is closed and tightened over the foot. However, while these approaches offer some improvements in mechanical coupling with the outer boot shell, they also tend to apply positive forces to the person's foot and are thus relatively uncomfortable over any significant period of time. Moreover, the use of injectable and/or curable foam elastomers provides limited mechanical coupling capability due to gradual inelastic deformation of the foam substance.
In one other proposed boot arrangement, a flexible chamber-forming member has been proposed at each side of the skier's foot wherein the chamber-forming member is partially filled with particulate such as plastic or glass beads. The chamber-forming member is then evacuated prior to use of the boot with the intent of rigidizing the particulate material in a shape generally conforming with the person's foot and thus provide an improved mechanical coupling with a rigid outer boot shell. See, for example, German Pat. No. 3,404,554. This arrangement, however, is impractical and essentially nonfunctional in use since the particulate material will tend to fall to the bottom of the chamber-forming member each time the boot is taken off the foot. When the skier subsequently reinserts his foot into the boot, the skier's foot will push the particulate material toward the bottom of the boot where it cannot engage or conform with upper zonal regions of the foot, ankle, and lower leg region.
The present invention overcomes the problems and disadvantages of the prior art by providing a further improved ski boot of the like having a specific arrangement of multiple flexible chambers filled partially with particulate material, wherein the chamber array is adapted to support and maintain the particulate material over the requisite anatomical zones of a skier's foot and lower leg region.